US2030861A - Tire retreading mold - Google Patents

Description

Feb. 18, 1936. M M I HER 2,030,81

TIRE RETREADING MOLD Filed June '26, 1934 3 Sheets-Sheet l 5 l I #95 I 54.48 68 50 I] [I 1'' 5, I2,

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TIRE RETREADING MOLD Filed June 26, 1954. s Sheets-Sheet 2 Feb. 18, 1936. M. M. FISHER TIRE RETREADING MOLD Filed June 26, 1934 5 Sheets-Sheet 3 ATTORNEYS Patented Feb. 18, 1936 UNITED STATES PATENT OFFICE 2,030,861 ma RETBEADlNG Mom Martin M. Fisher, Seattle, Wash. summation Jam 26, 1934, Serial No. 132,545

' Claims. (01. 18-18) My invention relates to a method and means for retreading tires and, more particularly, to a tire retreading mold. i

The relatively high initial cost of the larger.

5 tires, used particularly on the larger cars, busses and trucks, has created a need for a tire retreading mold, which can quickly and properly retread the wearing surface of tires so that the full life of the expensive tire carcassescan be used.

My present equipment is so constructed that it-permits of a new method of retreading tires, wherein the tire carcass is held substantially in an undistorted condition'and wherein the only portion of the tire that is cured is that imme- 5 diately adjacent the new rubber applied. This adds greatly to the life of the tire carcasses as the side walls and the margins of the original tread surfaces are maintained practically without rise in temperature. This has effected a great v economy as it adds so greatly to the wearing quality of the retreaded tire as against those retreads where the carcass itself is heated. With my method of retreading there is no danger of loosening up the bonding rubber that holds the layers of cord and fabric in place.

Another feature of my equipment is that it permits the retreading of a tire without the necessity of using bulky and unwieldy equipment that is often used to distort the tire carcass during the retreading operation.

Other and more specific objects will be apparent from thefollowing description taken in connection with the accompanying drawings, wherein Figure 1 is an elevation of a tire mold made after the'teachings of my invention.

Figure 2 is a vertical, sectional view through Figure 8 illustrates, in fragmentary form, the cross-section of a tire ready for application of the retread material.

Figure 9 illustrates the same section with the retread material cemented in place thereon. 5 Figure 10 illustrates a. portion ofthe'retread,

material before it is applied to the tire.

Referring to the drawings, throughout which like reference characters indicate like parts, l2, l4 and 16 designate a plurality of similar sego ments which go to make up my continuous mold. In the present illustrations I have shown three such, segments. This seems to be a desirable number, altho the number might be increased if they were-to be used on very large tires where 5' the weight might make them unwieldy to handle. Each of the segments is provided with an open steam chamber l8. This chamber, because of the relatively thin side walls, is strengthened by a plurality of lugs 20 which extend from one' 20 wall to the other and thus support the same against distortion when steam pressure is applied to chamber I8. As shown in Figure 6, particularly, I provide a plurality of tubes connecting the working face of the mold with the out- 25 side so that unwanted air can be driven'out thru the passage way.

To provide a definite engagement between the segments and to hold them in exactalignment, I

provide vertically disposed centering lugs 23 and 30 24 and, also, horizontally disposed lugs 25. These my tire mold showing a tire inflated ready for .is a matter of choice, altho I have found that,

curing.

9 Figure 3 illustrates, in perspective, the pinrality of segments making up my continuous mold. d

Figure 4 is a vertical, sectional view thru one of the joints of my mold.

Figure 5 is a face viewof one of the joints showing the centering means employed.

a Figure 6 is a cross-sectional view, as on the line 6-4 of Figure 4, showing particularly the method of venting my mold so that unwanted air can-escape.

Figure '7 is a perspective view showing the com- -pression band used to hold my mold in position andalso showing in exploded relationship, the compression rods and fixtures used to tighten 65 the band. I i

. the tire, as 31 is provided with a plurality of out- 6e if they are round, tight joints can be quite easily obtained. 40 .A steam supply pipe, as 82, is tapped intoone oi the segments so as to obtain free communicationwith the chamber l8. At each 0! the two joints, where sections l2 and I4 abut segment I6,

'I provldecommunicating openings as 33 so that 46 the steam will'be free to circulate thru the three sections and out the discharge pipe 34. This discharge pipe should preferably be provided with a valve as 35 so that the steam within the mold can be maintained 'at any desired pressure. The

' discharge pipe 34 should preferably be near the bottom of the mold so that-condensation will be carried out by the escaping steam.

The working face of the mold, which engages 5 be accomplished. It is very desirable that the pattern fomiing lugs, or rings, which engage the center of the tread be of less extent than those that engage the edges. This is to provide added thickness of cured rubber under the centrally ting of the new tread will be prevented. Lugs 39- are disposed at the outer edge of the retread material and serve as shears so that any material flowing out past them may be easily torn off the mold. The outer face 40 of the mold is provided with angular rings that extend outwardly considerably, as 4| and 42, which are adapted to engage and center the compression band 44, I find it desirable to hold the compression band somewhat away from face 40 so that the vent pipes}! will not be obstructed, further it is desirable to interrupt or cut away portions of ribs 41,42 and 45 so that a free flow of air can be at all times assured.

, Band 44 should be made, preferably, of steel that is fairly flexible and is folded back on itself at each endto'form loops as 48 and 49. These loops are intended to accommodate the pivotable pinsil and 52. These pins, in turn, are provided with enlarged heads, one on each end, as 54 and 55, which are adapted'to accommodate the threaded rods 51 and 58. A plurality of spacers 60 are provided to fit over rods 51 and 58, so that nuts 59 can be tightened on the tension rods 51 and 58 and squeeze the band together thus clo'sing the three segments of the mold about the tire.

In Figure 8 I have illustrated a section of the tire 82 prepared ready for treatment. The tread surface is finished smoothly so as to provide a firm base for the rubber tread 53, this is cemented to the times shown in Figure 9. In retreadjng a tire the new material 68 is usually placed upon the tire before the same is applied to its rim, or wheel. When it is desired to cure the rubber, the tire is then placedupon its rim, orwheel, and the three segments, comprising the mold, disposed around it. Band 44 is placed over the segments and, by means of tightening up rods 51 and 58, the mold is tightly seated on the tire, compressing it somewhat, particularly, the new rubber 63.

As soon as the three segments meet in tightengagement so as to complete the true circle, the tire with the mold attached is placed on the press table 65, after the showing of Figure 2., A plurality of wedges as 66 are inserted under the mold proper so as to hold it in position ,and to prevent its weight causing it to shift downwardly. The upper clamp member 68 is then lowered over the tire and tension screw 10 is engaged in its nut II. This nut is-relatively loose in hnb 12, hi h formed as part of table 65 and is securedin place by a plurality of set screws 13 which are not so tight as to hold it rigid but ratherto allow it to align itself with screw 10. Hand wheel 15 is then tightened and the tire is compressed between table 65 and clamp member 68, so as to more securely hold the mold in position.

. Just before the steam is turnedinto the mold itis founddesirable to inflate the tube so that the tread portion of the tire will not crowdaway from the mold when it becomes heated and semiplastic. The internal air pressure keeps the tread disposed grooves or indentations, so that splitto provide a plurality of outstanding ribs as 48 terminating at portion of the tire carcass fully pressed against the mold and facilitates forming the roughened I tread surface. It is desired to particularly point out, at this time, that the major portion of the pressure required during the curing operation is' provided by band 44 as it forces together the segments forming the mold. This pressure is increased by the press arrangement which tends to slightly flatten the side walls of the tire. Now

it should be remembered that the tires to which this equipment is particularly adapted are large, heavy carcasses, that will in themselves resist, to

a large degree, any distortion. The tire, even before air is applied, is under considerable compression, this compression is maintained,during the curingoperation, by virtue of the fact that excepting for that portion of the tire immediately-adjacen't the newly applied rubber, the balance of the tire is cold and the natural resiliency of the carcass provides, in a great measure, the pressure required for satisfactory vulcanizing of the tread material to the tire.

The foregoing description and the accompanying drawings are believed to clearly disclose a preferred embodiment of my invention but it will be understood that this disclosure is merely illustrative and that such changes in the invention may be made as are fairly within the scope and spirit ofthe following claims.

Having thus fully described my invention, what 30 I claim as new and desire to secure by Letters Patent is:-.-

1. In a tire retreader the combination with a tire support and an annular clamp ring adapted to engage the upper wall of said tire, and means 35 for compressing said ring, of a plurality of arcuate segments having steam heating passageways therethrough, horizontal tubes through said segments, and a series of spaced, exterior rings thereon, co-acting means on adjoining ends of said segments making air tight connections between said steam passageways, and anexterior, annular, clampring surrounding said segments and co-acting with said spaced rings for outlet of excess air, and clamping means therefor.

2. In a tire retreader, the combination with a tire support having a central bearing-nut, an annular clamp ring engaging the upper wall of a tire, and a screw bar Journaled in the clamp ring and f threaded in said nut for compressing the 50 ring on the tire, of a plurality of arcuate segments having steam heating passages therethrough. centering lugs and recesses on adjoining ends of said segments forming air tight connections therebetween, an exterior annular clamp ring surrounding the segments. and means for clamping the last mentioned ring on said segments.

3. In a tire retreader, the-combination with a tire support, a clamp ring to engage the upper wall of a tire, and-means for compressing the ring on the tire, of a plurality of arcuate segments having steam-heating passages therethrough, transversely arranged vent tubes in said segments opposite ends thereof, co-acting oining ends of said segments for means on 'making steam tight connections between said located between the spaced centering lugs and l in contactfwith the spacing lugs. and clamping means, for the clamp ring. Y

4. A tire retreader comprising a plurality of arcuate segments having steam-heatinges therethrough, co-acting vertical lugs and r I 76 and co-acting horizontal lugs and recesses on adjoining ends of and forming joints between said segments, one set of lugs and recesses at each joint making air-tight connection between adjoining passages, and means for clamping said segments in operative position.

5. A tire retreader comprising a pluralityof arcuate segments having steam heating passages therethrough and steam connections between ad- 10 joining ends of said segments, means for intro- MARTIN M. FISHER. 10

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